One type of vehicle suspension system which is becoming increasingly popular is the MacPherson strut suspension system. The MacPherson strut is an integral coil spring-shock absorber assembly which provides a lightweight, compact component of a vehicle suspension system. The MacPherson strut suspension system is disclosed in more detail in U.S. Pat. No. 2,624,592 to E. S. MacPherson.
One of the problems associated with MacPherson strut assemblies is related to the replacement of a worn shock absorber unit. One solution to this problem is to manufacture the MacPherson strut assembly with a construction which permits the shock absorber to be readily removed and replaced with a new shock absorber. However, this type of construction results in additional manufacturing expense. Consequently, some manufacturers produce MacPherson strut assemblies which do not readily accept replacement shock absorbers. In this type of assembly, the original equipment shock absorber unit is inserted into an associated cylindrical shroud which is subsequently sealed by welding or roll forming. The cylindrical shroud typically includes a lower coil spring support platform and a lower support bracket. Thus, when the shock absorber unit wears out, the vehicle owner is faced with the expense of replacing the entire cylindrical shroud assembly, including the coil spring support platform and the lower support bracket.
One solution to the problem of rebuilding a factory sealed cylindrical shroud assembly has been proposed in U.S. Pat. No. 4,256,421 to Kenneth D. Kloster. The Kloster patent discloses a self-threading nut which can be utilized to hold a replacement shock absorber unit within the cylindrical shroud of a MacPherson strut suspension system. If the original shock absorber of the MacPherson strut is factory sealed within the cylindrical shroud, the upper end of the cylindrical shroud must first be severed to provide access to the original shock absorber. After the upper end of the cylindrical shroud is severed, the worn shock absorber can be removed and replaced with a new shock absorber. The self-threading nut disclosed in the Kloster patent can then be used as a permanent retainer to hold the replacement shock absorber in the cylindrical shroud.